Nephrolithiasis is common, affecting up to 10% of the population. Symptomatic stone episodes produce significant pain and suffering, as well as great individual and societal economic costs. Much effort has been directed towards understanding metabolic abnormalities that can increase urinary supersaturation, which is clearly one key factor that initiates and favors stone growth. However, crystal-crystal and crystal-cell interactions also appear to be critical events during the early stages of stone formation. Therefore, increased understanding of the factors that modulate the interface of urinary proteins and crystals, and hence their subsequent interaction with other crystals or cells, is a necessary prerequisite for identifying new therapeutic targets. Such knowledge will in turn enable development of new strategies for the treatment and prevention of renal stone disease. Therefore, the urinary phenotyping core will serve 4 key functions in support of this Urology O'Brien Center: 1) Quantification of urinary components of the supersaturation profile 2) Quantification of urinary inhibitor activity 3) Renal biopsy processing, including staining of sections, and quantification of calcifications 3) Biobanking of urine, blood, renal tissues, and stones The Urinary Phenotyping Core will directly support Projects 2 and 3, and it will likely be of value for pilot projects initiated during the Center's activities that require biobanked samples or urinary assays.